The invention relates to improvements in vibration damping apparatus, and more particularly to improvements in apparatus wherein a prime mover (such as an internal combustion engine) transmits torque to one or more driven components by way of one or more endless flexible elements in the form of chains, bands, belts or the like. Still more particularly, the invention relates to improvements in vibration damping apparatus which can be utilized with advantage in power trains connected between the output elements of engines in motor vehicles and one or more driven components, such as pumps, fans, power steering devices, alternators, compressors and/or others.
A vibration damping apparatus which can be installed in a power train between a combustion engine and one or more driven components in a motor vehicle is disclosed, for example, in published German patent application No. 40 18 596. In that application there is disclosed an endless flexible torque transmission member in the form of a belt that is trained over several pulleys or sheaves, one of which is concentric with and receives torque from the output element (e.g., a crankshaft) of the engine. The vibration damping apparatus includes a torque transmitting device which is installed between the output element of the engine and the respective sheave and permits such sheave and the output element to turn relative to each other. The torque transmitting device includes ring-shaped damping elements which are made of rubber. Certain other prior proposals include the provision of different damping elements such, as coil springs. A drawback of heretofore known vibration damping apparatus is that they are overly complex and not sufficiently versatile to ensure adequate damping of vibrations under all of a number of different circumstances which can arise during operation of a motor vehicle.